[Access] Improve error messages when querying old blocks

[UlyanaAndrukhiv]

Closes: #4904

Context

This PR improves error messaging on Access nodes for block height-based queries:

• ExecuteScriptAtBlockHeight,
• GetBlockByHeight,
• GetBlockHeaderByHeight,
• GetEventsForHeightRange,
• GetAccountAtBlockHeight,
• GetAccountBalanceAtBlockHeight,
• GetAccountKeyAtBlockHeight,
• GetAccountKeysAtBlockHeight.

Errors are now categorized based on the queried height:

• Below Spork Root Height: Instructs the caller to use a historic node.
• Below Node’s Root Height: Suggests querying a different Access node (if the node was started after a spork).

Updated and added unit tests to validate the new messaging logic.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 77.41935% with 7 lines in your changes missing coverage. Please review.

Project coverage is 41.13%. Comparing base (ce74abc) to head (bf32c98).

Files with missing lines	Patch %	Lines
engine/access/rpc/backend/backend_accounts.go	20.00%	4 Missing ⚠️
engine/access/rpc/backend/backend_block_details.go	0.00%	1 Missing ⚠️
engine/access/rpc/backend/backend_block_headers.go	0.00%	1 Missing ⚠️
engine/access/rpc/backend/backend_scripts.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6554   +/-   ##
=======================================
  Coverage   41.12%   41.13%           
=======================================
  Files        2031     2031           
  Lines      179589   179611   +22     
=======================================
+ Hits        73862    73875   +13     
- Misses      99521    99528    +7     
- Partials     6206     6208    +2     

Flag	Coverage Δ
unittests	41.13% <77.41%> (+<0.01%)	⬆️

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[Guitarheroua]

LGTM 👍